Cross dyeing fiber blends of polyurethane, polyacrylate or butadiene-acrylonitrile copolymer coated cotton fibers with disperse and reactive dyes

ABSTRACT

A process has been developed for cross-dyeing cellulosic fabrics. This process consists of weaving certain polymer treated or polymer and crosslinking agent treated yarns into a fabric. Then the fabric is dyed with a disperse dye and a cotton dye. The polymer treated yarns are dyed with a disperse dye while the nonpolymer treated yarns are dyed with the cotton dye. This yields a cross-dyed fabric. The polymer treated yarns used in weaving are produced either by direct treatment, skein treatment or by knitting a fabric, treating the knit, deknitting and using these yarns in weaving.

United States Patent Harper, Jr. et al.

Apr. 2, 1974 CROSS DYEING FIBER BLENDS OF POLYURETHANE, POLYACRYLATE OR BUTADIENE-ACRYLONITRILE COPOLYMER COATED COTTON FIBERS WITH DISPERSE AND REACTIVE DYES Inventors: Robert J. Harper, Jr., Metairie;

Eugene J. Blanchard, New Orleans; John T. Lotton; Gloria A. Gautreaux, both of Metairie, all of La.

Assignee: The United States of America as represented by the Secretary of Agriculture, Washington, DC.

Filed: Nov. 5, 1971 Appl. No.: 196,210

U.S. Cl 28/72.16, 8/15, 8/17, 8/l8, 8/39, 8/1 E, 8/31, 117/15, 117/37 R, 117/62.1, ll7/l39.4, 117/145, 117/161 KP, 117/161 UC, 117/161 UD Int. Cl. D04!) l9/00, 606p 1/38 Field of Search 28/72.16, 18, 17

References Cited UNITED STATES PATENTS 1 1,610,786 ll/l972 Jacoby ..8/65X 3,508,854 4/1970 Sokol 8/18 FOREIGN PATENTS OR APPLICATIONS 396,219 ll/l9l0 Great Britain 28/72.l6

Primary Examiner-Donald Levy Attorney, Agent, or FirmM. Howard Silverstein The polymer treated yarns used in weaving are produced either by direct treatment, skein treatment or by knitting a fabric, treating the knit, deknitting and using these yarns in weaving.

10 Claims, No. Drawings 1 CROSS DYEING FIBER BLENDS OFv POLYURETHANE, POLYACRYLATE OR BUTADIENE-ACRYLONITRILE COPOLYMER COATED COTTON FIBERS WITH DISPERSE AND REACTIVE DYES A nonexclusive, irrevocable, royalty-free license in the invention herein described, throughout the world for all purposes of the United States Government, with the power to grant sublicenses for such purposes, is hereby granted to the Government of the United States of America.

This invention relates to the dyeing of cotton and other cellulosic fabrics. More particularly, this invention relates to a process which permits cotton and other cellulosic fabrics to be cross-dyed after crosslinking.

Heretofore, it is well known that disperse dyestuffs have little affinity for c ellulosic fabrics. Likewise, it is well known that only limited systems exist for dyeing of crosslinked fabrics. Furthermore, few systems exist which permit cotton fabrics to be cross-dyed. The selective dyeing of particular cotton yarns in fabrics would provide a route to fabrics that can only be achieved by the use of expensive dyed yarns.

This process is designed to achieve selective dyeing of various selectedcotton yarns in fabrics with disperse dyestuffs whether or not the fabric is crosslinked. This is achieved in the following manner. First, cotton yarns are treated with polymer to obtain polymer sized yarns. Then, these yarns are woven into fabrics. The fabrics at this point may or may not be crosslinked. In either case, when these fabrics are dyed with disperse dyestuffs, only those yarns which are polymer treated are dyed. By this method, it is possible to produce cotton fabrics in which only the warp yarns are dyed or only the filling yarns are dyed or only certain special yarns are dyed. For example, if only the warp yarns are polymer coated, then only the warp yarns would be dyed. Conversely, if only the filling yarns are coated, then only the filling yarns would be dyed. In another case, an 8 8 basket weave wasprepared in which the, filling yarns were changed from polymer treated to untreated yarns and back again in units of eight in the weave. When this fabric was dyed using a yellow disperse dye, a striped pattern in the filling direction was produced. This experiment indicates that a pattern effect can be produced on cotton fabrics by the use ofa piece-dyeing technique if the fabric is woven from yarns, only a portion of which have been treated and in which these treated yarns have been inserted in the fabric in a regular patterned fashion.

In order to achieve the cross-dye effect, a modification of the procedure is necessary. First, the fabric is woven from yarns in which only selected yarns have been polymer treated. Then, the fabric is dyed with a normal cotton dye such as a vat, direct or reactive dye. At this point, the fabric may be crosslinked. The fabric is next dyed with a disperse dye to achieve the crossdye effect. A modified process in which the crosslinking is omitted or performed last can also be used to produce cross-dyed fabrics.

Something should now be said about the method of applying the polymer to the yarns. One method is to apply the polymer to the warp yarns at or in the slashing operation. Filling yarns can be treated in the skein form. A more elegant approach which has the advantage of rapid fabric treatments consists of the following.

2 First, knit fabric is woven from the yarns which are to be polymer treated. The knit fabric is next treated with the appropriate polymer. Then the fabric is deknitted. These yarns are used entirely or selectively in either the warp or fill of the woven fabrics. By this method, the advantages of fabric chemical treatments are maintained while incorporating selective dyeing characteristics to woven goods.

The same procedure of knit, fabric treat and deknit has also been employed where the treatment consisted of a polymer and crosslinking agent. This method makes the polymer treated yarns more resistant to cotton dye thus permitting a sharper delineation of colors.

The ability to dye these fabrics prepared from polymer treated yarns is valuable from several viewpoints. First, the use of permanent polymers in sizing formulations becomes more attractive because cross-dyeing techniques can now be applied to woven fabrics prepared from polymer sized yarns. Because dyeing difficulties have been a major objection to the use of such a technique in industry, this is important. Second, the. ability to dye a cotton fabric subsequent to crosslinking is particularly important because heretofore crosslinked cotton fabrics have had poor affinity for dyes. This means that fabric producers have had to maintain large inventories of finished fabrics in all dye shades. However, if the option were present to dye fabric subsequent to crosslinking, fabric inventory could be reduced drastically.

The final aspect of this approach is that it permits the dyer to use piece-dye techniques on woven goods in such a 'manner that designs are produced on fabric. When the proper polymers are applied to yarns and then these yarns are woven into fabric, selective dye uptake occurs on these yarns only and not on-the untreated cotton yarns when these fabrics are piece-dyed using disperse dyestuffs. Control of the pattern effect is achieved in accordance to how the polymer treated yarns are inserted into the fabric.

While this method has been employed only with allcotton yarns, this approach should also be effective with a blend of polyester-cotton yarn.

While a number of polymers and copolymers have been used in finishing prior to dyeing, only those with relatively low functionality such as polyethylene perform poorly. Polyacrylate copolymers are moderately effective. Polyurethanes are further effective and particularly effective are butadiene-acrylonitrile copolymers. In this respect it can be readily seen that nitrile, urethane or amide linkages are preferred groups in polymers to promote disperse dyestuff absorption. From a practical point of view, polymers with glass transition temperatures below room temperature would appear to bemost suitable. Dye uptake can be achieved with polymers of high glass transition temperatures but the high add-ons required in this process lead to fairly stiff fabrics.

Numerous polymers are available to promote dye uptake. It is only necessary to select those which possess the desired functionality or chemical groups that when used in fibers or films have shown good affinity for disperse dyes. Some groups which are particularly effective are CH7(I3H o III I N O H 1 Lease type linkage is formed. Acrylate copolymers likewise have shown good performance as well as butadienestyrene copolymers. Once the requirement for dye acceptability of the polymer becomes recognized, the process variables can be easily worked out by anyone knowledgable in the textile field. The polymer can be applied to the yarnseither as an emulsion or from solvent. Once the initial phase of this work is accomplished (namely, the yarns are polymer treated and incorporated in the fabric), the next step consists of the application of the disperse dyestuff to the fabric. The method most commonly employed in this work was placing the disperse dyestuff in a bath and heating the fabric at an elevated temperature in the dyebath containing the disperse dyestuff. Because crosslinking finishes are sensitive to bath pH at higher temperatures, an important consideration is to use dyestuffs and baths which can be adjusted close to pH 7 if necessary.

In addition to dyebath techniques, other methods usually employed with disperse dyestuffs can also be utilized. One such method is the thermosol method, which is a high temperature fixation method frequently employed with synthetic fabrics. While the nature of the polymers employed in this work is such that dyebath techniques would seem to be preferred, the application of the thermosol method using dyestuffs with low sublimation characteristics should be possible. In particular, this method should be appropriate for blended fabrics in which the synthetic component may be dyed most easily using the thermosol process.

Some additional comment should be made concerning the fact that the polymer treated yarns can be effectively dyed whether or not they are crosslinked. As such, the fabric can be crosslinked and then dyed. This offers a degree of flexibility so that for inventory control or for some other purpose, disperse dyeing can be postponed until it is the last step in finishing. Thus, in this sequence the fabric is prepared using polymer sized yarns, the fabric is crosslinked and then the fabric is dyed.

In another aspect of this work, it is possible to achieve a cross-dyed effect by dyeing fabrics prepared from polymer sized and untreated cotton yarns either sequentially or in a single treatment with a combination of cotton and disperse dyes. By this method, it is possible to produce fabrics by piece-dyeing procedures that otherwise give the impression of being prepared from yarn-dyed fabrics. This occurs because the disperse dye is taken up only by the polymer treated yarns while the normal cotton dye (reactive, direct or vat) is taken up by both yarns but to a lesser extent by the polymer treated yarn. By proper selection of colors and due to the fact that the polymer is on the exterior of the fibers,

this results in a bicolored fabric. That is, the polymer treated yarns take on the color of the disperse dye while the cotton yarns take on the color of the reactive or other cotton dyer The amount of cotton dye absorbed by the polymer treated yarns can be reduced if these yarns are crosslinked prior to the fabric treatment with the reactive dye. This variation can be achieved if the polymer treated yarns are also treated with crosslinking agent. This again can be achieved either simultaneously or sequentially, the only requirement being that the crosslinking application is done on the yarn prior to the insertion of the yarn in the fabric. in this case, curing can be done either before or after weaving.

in addition to the application described, fabrics with candy-striped yarns can also be prepared using fabric dyeing procedures. This can be achieved by preparing polymer treated yarns or yarns treated with polymer and crosslinking agent by any method heretofore described, plying this yarn with an untreated yarn and then dyeing the fabrics prepared from these yarns with a disperse dye and a cotton dye.

To this point, little consideration has been given to how much polymer is required for these treatments. To be sure, dye uptake increases progressively as the amount of polymer applied to the fabric is increased. An effective area of polymer application seems to be from 4 25 percent with the preferred range being from 7 18 percent taking into consideration matters such as effectiveness, fabric hand, cost and other factors influencing fabric use. By use of a polymer with higher dye affinity, the lower end of the polymer concentration range can be used and conversely, with polymers with lower dye affinities, polymer concentrations at the higher treatment range may be necessary.

The following examples are intended to be representative of treating solutions rather than limiting. Numerous variations are possible for anyone practiced in the textile art.

EXAMPLE 1 A skein of cotton yarn was dipped into a solution containing 12 percent polyurethane. The skein was then squeezed on a pad roll, dried for 10 min. at C and cured for 10 min. at 140 C.

A similar treatment was employed using a bath containing 12 percent polyacrylate. A third skein of cotton yarn was given a similar treatment with a bath containing 12 percent butadiene-acrylonitrile copolymer. These various yarns were then woven into basket weave fabrics in which the polymer treated yarns were used for the filling of the fabrics. After these fabrics had been desized they were then dyed with Disperse Yellow 34. The dyebath contained 1 percent Disperse Yellow 34 with the bath temperature being C and the samples being dyed for a period of 25 min.

These samples with the polymer treated filling yarns were dyed yellow while the warp yarns were undyed. The control fabric in which neither the warp nor the filling was polymer treated was likewise undyed. This example demonstrates that selective dye uptake can be achieved with piece dyeing provided a fabric is prepared from yarns with only a portion of these being polymer treated. The disperse dye is selectively absorbed on the yarns which have been polymer treated. All that is required is that polymer treated yarns be used where subsequent dye uptake is desired.

EXAMPLE 2 Several skeins of cotton yarn were treated with a solution containing 25 percent polyurethane. The skeins were then squeezed on a pad roll, dried for min. at 70 C and cured for 10 min. at 140 C. Some of these yarns were used for the filling in an 8 X 8 basket weave with standard warp yarns.

The remainder of the polymer treated yarns was employed in the following manner. An 8 X 8 basket weave fabric was prepared in which the filling yarns were composed of alternating bands inch wide) of polyurethane treated yarns and untreated cotton yarn. These two fabrics were then dyed for a period of 30 min. at 90 -l00 C in a bath containing 1 percent Disperse Yellow 88. The samples were then rinsed, laundered and tumbled dry. The fabric in which all of the filling yarns were polymer treated showed a checked orange and white pattern. This was caused by the fact that the disperse dye was absorbed only on the polymer treated filling yarns but not on the untreated warp yarns.

In the second fabric a striped pattern effect was produced in the filling. This was due to the fact that every of an inch the filling yarn was alternated between polymer treated and untreated yarns. This example demonstrates that a pattern can be produced from piece dyeing provided that selective positioning of polymer treated yarns is employed and subsequent dyeing is performed using adisperse dye.

Similar results were observed when these same fabrics were dyed with either 1 percent Disperse Red 86 or 1.5 percent Disperse Blue 79 at 80-90 C for a period of 1 hr., except that the polymer treated yarns were dyed red orblue, respectively.

EXAMPLE 3 In this case, the woven fabrics in example 2 were treated with crosslinking agent prior to dyeing. The crosslinking treatment consisted of the following. The fabrics were padded with a solution containing 9 percent dimethylol .dihydroxyethyleneurea and 0.6 percent zinc nitrate hexahydrate. The fabrics were dried for 7 min. at 60 C, cured for min. at 130C, then washed and tumbled dry. These fabrics were then dyed with Disperse Red 86 and Disperse Blue 79 using the procedure described in example 2. The. polymer treated yarns were dyed a deep red or blue, respectively, while the yarns without the polymer treatment were only weakly dyed.

This result demonstrates that this process provides a mechanism by which selected yarns could be dyed subsequent to crosslinking.

EXAMPLE 4 Two tubes of circular knitted fabrics were prepared. Each tube was padded with a solution that contained 12 percent polyurethane, 4.5 percent dimethylol dihydroxyethyleneurea and 0.4 percent nitrate hexahydrate. In one case, the glass transition temperature of the polyurethane was 0, while in the other case the glass transition temperature was -50 C. The resins were dried on the knitted fabrics and then the fabrics were deknitted. These yarns were then used as filling in a 2 X 2 basket weave. The woven fabrics were cured for 15 min. at 130- C and then rinsed and tumbled dry. These fabrics were desized in a solution containing 0.3

percent Rhozyme DX at 70 C for a period of 30 min., then washed and tumbled dry.

Samples from these fabrics were then cross-dyed using the following procedure. First the fabrics were dyed with Reactive Blue 4 using a standard dye procedure.

Essentially this consisted of inserting the fabrics into a room temperature bath containing 2 percent dye (based on weight of water) and 40 percent sodium sulfate (based on weight of fabric). The samples were stirred for 15 min., removed from dye bath, 30 percent sodium carbonate (based on weight of fabric) was added and then fabric samples were reinserted in dyebath and stirred for 15 min. The fabrics were rinsed in cold water and then heated in a hot bath containing a wetting agent.

Samples of this fabric were then dyed with a disperse dye, 1.5 percent Disperse Yellow 88, using the procedure followed in Example 2. Other samples of fabric dyed with the reactive blue dye were also dyed with Disperse Red 86 and with lntrasil Orange 5 RL using the same procedure as with Disperse Yellow 88. In each case, a cross-dyed fabric was produced. The warp yarns of the fabric were dyed blue while the filling yarns were dyed yellow, red or orange, depending upon the color of the disperse dye used in the dyebath. These results show that this procedure yields a process which permits cotton fabrics to be cross-dyed using piece dyeing procedures.

EXAMPLE 5 Two fabrics were prepared in analogous fashion to those in example 4 except that the chemical treatment on the knitted sock was polymer only. In one case, the chemical treatment was with l2percent polyurethane with a low-glass transition temperature and in the second case the treatment was with a nitrile copolymer (12 percent) of low-glass transition temperature.

The fabrics were cross-dyed using two procedures. In one case, samples of these fabrics were initially dyed with 1.0 percent Disperse Blue 79 using the same procedure as in example 4. Subsequently, the fabrics were dyed with a reactive dye using the same procedure employed in example 4. The reactive dyes used were Reactive Blue 4, Reactive Orange 4, Reactive Red 1, and Reactive Yellow 22. In each case, the filling yarns were dyed a navy blue while the warp yarns were dyed blue, orange, red, or yellow depending upon the color of the reactive dye employed. This demonstrates again that this procedure yields cross-dyed cotton fabrics. In each case, a patterned effect was produced because the fabrics were dyed one color in one direction while they were dyed another color in the second direction.

The reverse procedure was also employed to achieve comparable cross-dyed fabrics, that is, the fabric was dyed with a reactive dye first and then dyed with the disperse dye. Y

This cross-dyed effect arises due to the fact that the disperse dyes dye only the polymer treated yarns while the reactive dyes dye both the untreated yarns and the interior of the polymer treated yarns.

We claim:

1. A process for producing a cross-dyed cotton fab- 5 ric, which process consists of:

a. treating a selected yarn portion of the total yarns that are to be formed into fabric with l-25 weight percent, based on the weight of the selected yarn portion, of a polymer selected from the group consisting of a polyurethane, a polyacrylate, and a butadiene-acrylonitrile copolymer, b. forming the total yarns, including the polymer treated selected yarn portion, into a fabric, and c. dyeing the formed fabric first with a cotton reactive dye and subsequently with a disperse dye thereby to produce a dyed fabric wherein the polymer treated yarn portions are dyed the color of the disperse dye and the remainder of the yarns are dyed the color of the cotton reactive dye. 2. The process of claim 1 wherein the polymer is a polyurethane.

3. The process of claim 1 wherein the polymer is a polyacrylate.

4. The process of claim 1 wherein the polymer is a butadiene-acrylonitrile copolymer.

5. The process of claim 1 wherein the fabric is crosslinked prior to dyeing.

6. A process for producing a cross-dyed cotton fabric, which process consists of:

a. knitting a fabric from a selected yarn portion of the total yarns that are to be formed into the fabric, b. treating the knitted fabric from step (a) with 1-25 weight percent, based on the weight of the knitted fabric, of a polymer selected from the group consisting of a polyurethane, a polyacrylate, and a butadiene-acrylonitrile copolymer.

c. deknitting the polymer treated knit fabric from step (b),

d. forming the total yarns, including the knitted, polymer treated and deknitted yarn portion, into a fabric,

e. dyeing the formed fabric from step (d) with a cotton reactive dye and subsequently with a disperse dye, thereby to produce a dyed fabric wherein the polymer treated yarn portions of the fabric are dyed the color of the disperse dye and the remainder of the yarns are dyed the color of the cotton reactive dye.

7. The process of claim 6 wherein the polymer is a polyurethane. I

8. The process of claim 6 wherein the polymer is a polyacrylate.

9. The process of claim 6 wherein the polymer is a butadiene-acrylonitrile copolymer.

10. The process of claim 6 wherein the fabric is crosslinked prior to dyeing. 

2. The process of claim 1 wherein the polymer is a polyurethane.
 3. The process of claim 1 wherein the polymer is a polyacrylate.
 4. The process of claim 1 wherein the polymer is a butadiene-acrylonitrile copolymer.
 5. The process of claim 1 wherein the fabric is crosslinked prior to dyeing.
 6. A process for producing a cross-dyed cotton fabric, which process consists of: a. knitting a fabric from a selected yarn portion of the total yarns that are to be formed into the fabric, b. treating the knitted fabric from step (a) with 1-25 weight percent, based on the weight of the knitted fabric, of a polymer selected from the group consisting of a polyurethane, a polyacrylate, and a butadiene-acrylonitrile copolymer. c. deknitting the polymer treated knit fabric from step (b), d. forming the total yarns, including the knitted, polymer treated and deknitted yarn portion, into a fabric, e. dyeing the formed fabric from step (d) with a cotton reactive dye and subsequently with a disperse dye, thereby to produce a dyed fabric wherein the polymer treated yarn portions of the fabric are dyed the color of the disperse dye and the remainder of the yarns are dyed the color of the cotton reactive dye.
 7. The process of claim 6 wherein the polymer is a polyurethane.
 8. The process of claim 6 wherein the polymer is a polyacrylate.
 9. The process of claim 6 wherein the polymer is a butadiene-acrylonitrile copolymer.
 10. The process of claim 6 wherein the fabric is crosslinked prior to dyeing. 